Shifting mechanism



2 4 o e m w s. w 2 6 I 4 TINY w R i-= 9 W w 6 v G I n-a I p I FIG.

INVFNTOR LEWIS ATTORNEYS Nov. 24, 1970 s. E. LEWIS SHIFTING MECHANISMOriginal Filed Sept. 20, 1965 United States Patent Oflice Re. 26,989Reissued Nov. 24, 1970 26,989 SHIFTING MECHANISM George E. Lewis,Hialeah, Fla., assignor to Power-Flo Products, Inc., Oakland Park, Fla.,a corporation of Florida Original No. 3,370,477, dated Feb. 27, 1968,Ser. No. 488,393, Sept. 20, 1965. Application for reissue June 9, 1969,Ser. No. 835,885

Int. Cl. F16h 5/08 US. Cl. 74--337.5 10 Claims Matter enclosed in heavybrackets I: appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

ABSTRACT OF THE DISCLOSURE Shifting mechanism including an output shaft,a plurality of gears of different size mounted for rotation on theoutput shaft at fixed axial positions therealong, clutch structurespositioned between adjacent one of the gears mounted on the output shaftfor axial movement therealong and against relative rotation with respectthereto for engagement with different ones of said gears in accordancewith the axial position of the clutch structures for alternativelyconnecting difierent ones of said gears for driving the output shaft ina plurality of speeds in one direction and at least one speed in theopposite direction, means connected to said gears for continuouslydriving the gears in the one and opposite direction, fork means engagedwith the clutch structures for moving them into and out of engagementwith the gears, a cam shaft for rotation in opposite directions and cammeans operable between the cam shaft and forks for moving the forks tosuccessively engage alternatively different gears separated by neutralpositions to provide reverse, first, second and third speeds for theoutput shaft.

In one modification the fork means includes a pair of forks havingsleeve portions with cam surfaces at the relatively remote ends thereofurged in opposite directions by spring means positioned therebetweensleeved over a camming sleeve secured to the cam shaft for rotationtherewith including camming pins engaged with the outer ends of thesleeve portions of the forks for moving the forks in accordance with thecam surface on the ends thereof on rotation of the cam shaft.

In another modification the fork means includes a pair of forks havingsleeve portions rotatably sleeved on the cam shaft, a pair of cam platesupporting members secured to the cam shaft at the opposite ends of theforks for rotation with the cam shaft, a cam plate secured to the platesupporting members having cam slots therein and cam pins extendingthrough the cam slots and secured to the fork sleeves.

In the past shifting mechanism for transmission structures even in thecase of simple transmission structures have usually required complexmovement of a shifting member such as a rod or shaft which complexmovement may include axial movement, rotational movement and movement ina plurality of directions about a pivot point. Such shifting mechanismsrequire special knowledge of the direction of movement and positionrequired of the shifting rod or shaft for each separate direction andspeed ratio provided by the transmission structure. In addition suchshifting mechanisms are undesirable in that they have in the past beencomplicated, uneconomical and often inefficient.

Wherein it has in the past been attempted to provide shifting mechanismin which movement of a shifting member in a single direction hasaccomplished the shifting between directions and speed ratios providedby a transmission the shifting mechanism has similarly been particularlycomplicated and thus uneconomical. Further, prior shifting mechanisms ofthis type have often been inefiicient or have lacked the requiredversatility necessary for use with transmission structure providing aplurality of speeds in one direction and at least one speed in anopposite direction.

It is, therefore, one of the objects of the present invention to provideimproved shifting mechanism for use with transmission structures or thelike.

Another object is to provide shifting mechanism for shifting between aplurality of transmission speeds in one direction and at least onetransmission speed in the opposite direction on rotation of a singleshifting shaft.

Another object is to provide Shifting mechanism for transmissionstructure including a plurality of gears driven in one direction and atleast one gear driven in the opposite direction including an outputshaft, a plurality of gears mounted on the output shaft in mesh with thetransmission structure gears, clutch structures mounted on the outputshaft for selectively connecting the output shaft to the gears thereonon movement thereof, shifting forks engaged with the clutch structures,a cam shaft carrying the shifting forks and cam means on the cam shaftoperable in conjunction with the shifting forks to move the clutchstructures axially of the cam shaft to connect the output shaft with aselected one of said plurality of gears.

Another object is to provide shifting mechanism as set forth abovewherein the shifting forks have cam surfaces thereon and the cam meansincludes cam pins in spaced apart relation to each other on the camshaft with the shifting forks therebetween and resilient means operablebetween the shifting forks for urging the cam surfaces on the shiftingforks into engagement with the cam pins on the cam shaft.

Another object is to provide shifting mechanism as set forth abovewherein the cam means includes a cam pin on each of the shifting forksand a cam plate secured to the cam shaft for rotation therewith havingseparate cam slots therein receiving the separate cam pins.

Another object is to provide shifting mechanism which is simple inconstruction, economical to manufacture and eflicient in use.

These and other objects and features of the invention will becomeapparent as the description proceeds, especially when taken inconjunction with the accompanying drawing, illustrating a preferredembodiment of the invention, wherein:

FIG. 1 is a perspective view of shifting mechanism constructed inaccordance with the invention.

FIG. 2 is a perspective view of modified cam structure for the shiftingmechanism illustrated in FIG. 1.

FIG. 3 is a diagrammatic representation of a cam configuration for usein the shifting mechanisms illustrated in FIGS. 1 and 2.

With particular reference to the figures of the drawing. one embodimentof the present invention will now be considered in detail.

As shown best in FIG. 1, the shifting mechanism 10 includes clutchstructures 12 and 14, the shifting forks 3 16 and 18, cam shaft 20 andspring 22. The shifting mechanism is illustrated in conjunction withdriven gears 24, 26, 28 and 30 in mesh with gears 32, 34, 36 and 38respectively on the output shaft 44.

In operation, the shifting forks 16 and 18 are moved to position theclutch mechanisms 12 and 14 so that the gears 38, 36, 34 and 32 aresuccessively connected to the output shaft 44 on the rotation of theshaft 20 in a clockwise direction from a counter-clockwise limitingposition.

More specifically, the driven gears 24, 26 and 28 may be connected to afirst driven shaft 40 for driving the gears 24, 26 and 28 in apredetermined direction which may be considered a forward direction. Thegear 30 is similarly connected to a driven shaft 42 for driving the gear30 in an opposite direction which may be considered a reverse direction.The drive structure for the shafts and 42 form no part of the presentinvention and therefore will not be considered in detail herein.

The separate gears 32, 34, 36 and 38 are secured to the output shaft 44by convenient means such as the collars 46 for rotation with respect tothe shaft 44 in a fixed axial position on the shaft 44. The gears 32, 34and 36 are meshed with the gears 24, 26 and 28 and are rotated by thegears 24, 26 and 28 in a direction to provide three forward speeds inaccordance with the gear ratios for the output shaft 44 when connectedto the drive shaft 44 for rotation therewith. The gear 38 is meshed withthe gear 30 whereby the gear 38 provides rotation of the output shaft 44in a reverse direction when connected to the output shaft 44 forrotation therewith.

The clutch structures 12 and 14 are the same. Therefore, only clutchstructure 12 will be considered in detail. The clutch structure 12 is ahollow cylindrical member 48 having dogs 50 on the opposite side thereoffor engagement with similar dogs on the adjacent sides of the gears 36and 38 on axial movement of the hollow cylindrical member 48 in oppositedirections along the output shaft 44. The hollow cylindrical member 48includes the annular groove 52 axial centrally thereof. The clutchstructure 12 is connected to the output shaft 44 for axial movement withrespect thereto and is fixed rotationally with respect thereto by splinemeans 54 operable therebetween.

In operation on axial movement of the clutch structure 12 on outputshaft 44 in opposite directions, the clutch structure 12 will connectthe output shaft 44 to the gear 36 on movement to the left in FIGURE 1and will connect the output shaft 44 to the gear 38 on movement to theright in FIGURE 1. Similarly, the clutch structure 14 on movement to theleft in FIGURE 1 will connect the gear 32 to the output shaft 44 due toengagement of dogs on the gear 32 with the dogs 50 on the clutchstructure 14. On movement to the right in FIGURE 1, the clutch structure14 connects the gear 34 with the output shaft 44.

The clutch structures 12 and 14 are moved axially of the drive shaft 44by the shifting forks 16 and 18 respectively. The shifting forks 16 and18 are similar. There fore, only the shifting fork 18 will be consideredin detail.

The shifting fork 18 is provided with a semi-circular notch in the end56 thereof fitting within the annular recess 52 of the clutch structure14. A hollow cylindrical portion 58 is provided on the upper end of theshifting fork 18 which cylindrical portion is sleeved over the camsleeve 60 for axial movement with respect to the cam shaft 20 onrotation of shaft 20. A cam surface 62 is provided on one end of thecylindrical portion 58 of the shifting fork having a cam contour similarto that illustrated in FIGURE 3 at the left. The shifting fork 16differs from the shifting fork 18 in that the cam surface 64 thereof issimilar to the cam surface illustrated in FIGURE 3 at the right.

The shifting forks 16 and 18 as indicated above are sleeved over the camsleeve for axial movement with respect thereto. The cam sleeve 60 issecured to the cam shaft 20 for rotation therewith about thelongitudinal axis 66 of the cam shaft 20. The cam pins 68 and 70 extendperpendicularly from the cam sleeve 60 for rotation with the cam shaft20. Spring 22 urges the shifting forks 16 and 18 away from each other sothat the cam surface 62 engages the cam pin 70 and the cam surface 64engages the cam pin 68.

In overall operation of the shifting mechanism 10 with the shaft 20 in afull counter-clockwise direction, the pin 70 engages the cam surface 62to maintain the fork 18 in a neutral position while the pin 68 engagesthe cam surface 64 to permit movement of the clutch structure 12 toconnect the gear 38 with the output shaft 44 whereby reverse rotation isimparted to the output shaft 44. The relative position of the camsurfaces 62 and 64 and pins 70 and 68 are illustrated in FIGURE 3 at theline indicated R at the right for reverse rotation of the shaft 44.

As the cam shaft 20 is rotated clockwise into the position indicated bythe line N at the right in FIGURE 3, the cam surfaces 64 and 62 are suchthat the shifting fork 18 will remain in the neutral position asillustrated in FIGURE 3 and the fork 16 will be returned to the neutralposition as illustrated on the line N at the right in FIGURE 3. Thus, inthe neutral position both of the clutch structures 12 and 14 are out ofengagement with the gears 32, 34, 36 and 38.

On continued rotation of the shaft 20 in a clockwise direction clutchstructure 12 moves to the left from the neutral position to connect thefirst gear 36 with the output shaft 44 whereby a first or low forwardspeed is imparted to the shaft 44. The clutch structure 14 is stillmaintained in a neutral position as illustrated in FIG- URE 3. Continuedrotation of the shaft 20 in the clock wise direction brings the clutchstructure 12 back to the neutral position again as shown in FIGURE 1.

As the cam shaft 20 is rotated still further in a clockwise directionthe shifting fork 16 and clutch structure 12 are maintained in a neutralposition due to the inner action between the cam pin 68 and cam surface64. However, the shifting fork 18 is moved to the right whereby theclutch structure 14 connects the second gear 34 with the output shaft 44to produce rotation thereof at a second forward speed.

Similarly, continued rotation of the cam shaft 20 clock wise will returnthe shifting fork 18 and clutch structure 14 to the neutral positionwhile maintaining the shifting fork 16 and clutch structure 12 in theneutral position and will subsequently move the shifting fork 18 into aposition whereby the gear 32 is connected by clutch structure 14 todrive shaft 44 to provide a third forward speed of rotation thereofwhile the shifting fork 16 is maintained in a neutral position.

With the shifting mechanism shown it will thus be evident that theshifting mechanism may be returned to neutral from any speed ratio.However, none of the speed ratio gears may be skipped in returning thecam shaft 20 to the ultimate neutral position between the reverse andfirst forward gear ratio position. Thus, the skipping of gear ratioswhich is detrimental to the transmission and shifting mechanism isprevented while a complete gear ratio range for forward speeds and areverse speed is provided in accordance with the shifting mechanism 10which is simple, economical and efficient.

The modified shifting mechanism 98 illustrated in FIG- URE 2 is similarto the shifting mechanism illustrated in FIGURE 1 except that theshifting forks 72 and 74 are provided with cam follower pins 76 and 78secured thereto and a cam plate 80 is mounted on the cam shaft 82 forrotation therewith by means of the annular discs 84 at each end thereof.The cam pins 76 and 78 are positioned in cam slots 86 and 88 in the camplate 80 which are formed in the manner of the cam surfaces 62 and 64 toprovide movement of the shifting forks 72 and 74 similar to the movementof the shifting forks 16 and 18. Again the cam shaft 20 is mounted in afixed axial position in the bearings 90 and 92 similar to the bearings94 and 96 rotatably mounting the cam shaft 20 in a fixed positionaxially.

The operation of the modified shifting mechanism 98 illustrated inFIGURE 2 is exactly the same as the shifting mechanism 10. While oneembodiment of the present invention and one modification thereof havebeen considered in detail, it will be understood that other embodimentsand modifications of the invention are contemplated. It is the intentionto include all embodiments and modifications as are defined by theappended claims within the scope of the invention.

What I claim as my invention is:

1. In combination an output shaft, [at least a] first, second, third andreverse [gear] gears rotatably mounted on the output shaft, means forrotating the first, second and third gears in one direction and meansfor rotating the reverse gear in the opposite direction [for providing aplurality of rotational speeds of the output shaft in one direction andat least one speed of the output shaft in the reverse direction onconnection of the gears thereto for rotation], separate clutch[structure] structures mounted on the output shaft for rotationtherewith and movement axially thereof between the reverse and first andbetween the second and third gears respectively, [including an annularrecess centrally thereof,] a cam shaft, a camming sleeve mounted on thecam shaft for rotation therewith, a cam pin extending transverselyoutwardly from the camm ng sleeve at the ends thereof, a .pair ofshifting forks having sleeve portions sleeved over the camming sleevebetween the pins, cam ends on the sleeve portions of the shifting forksin engagement with the cam pins on the cam sleeve, resilient meansoperable between the adjacent ends of t he sleeve portions of theshifting forks urging the shifmg forks in opposite directions intoengagement with the cam pins on the cam sleeve [and fork ends on theshifting forks received within the annular recess of] and a fork end oneach shifting fork engaged with a respective clutch structure formovement of the clutch structures axially of the cam shaft and outputshaft on rotation of the cam shaft to engage the clutch structures withthe gears alternatively on rotation of the cam shaft in a singledirection.

2. Structure as set forth in claim 1, wherein the cam surfaces on theshifting forks [are designed and constructed to] move the shifting forksto successively engage a clutch structure with the reverse, first,second and third gears with a neutral fork position in which no gear isengaged with a clutch structure between engagement of each of the gearswith a clutch structure on rotation of the cam shaft in a singledirection.

3. In combination an output shaft, [at least a] first, second, third andreverse [gear] gears rotatably mounted on the output shaft, means forrotating the first, second and third gears in one direction and meansfor rotating the reverse gear in the opposite direction [for providing aplurality of rotational speeds of the output shaft in one direction andat least one speed of the output shaft in the reverse direction onconnection of the gears thereto for rotation with the output shaft],separate clutch [structure] structures mounted on the output shaft forrotation therewith and movement axially thereof between the reverse andfirst and between the second and third gears respectively, [including anannular recess centrally thereof,] a cam shaft, a pair of shifting forksmounted on the cam shaft for movement axially thereof, each including asleeve portion sleeved over the cam shaft and cam pins extending out ofthe sleeve portion of the shifting forks, a forked end on each of theshifting forks [received within the annular recess of] engaged with arespective clutch structure, a cam plate secured to said cam shaft overthe sleeve portions of the shifting forks for rotation with the camshaft having cam slots therein receiving the cam pins on the shiftingforks, whereby on rotation of the cam shaft the shifting forks are movedaxially of the cam shaft and output shaft to [engage] move the clutchstructures into engagement with predetermined ones of the gearsalternatively,

4. Structure as set forth in claim 3, wherein the cam slots [aredesigned and constructed to] move the shifting forks to successivelyengage a clutch structure with the reverse, first, second and thirdgears with a neutral fork position in which no gear is engaged with aclutch structure between engagement of each of the gears with a clutchstructure on rotation of the cam shaft in a single direction.

5. Shifting mechanism comprising a cam shaft, a cam sleeve secured tosaid cam shaft for rotation therewith, cam pins extending transverselyout of the cam sleeve at the opposite ends thereof, shifting forkshaving sleeve portions at one end thereof mounted for axial movement onthe cam sleeve between the pins, said sleeve portions having cam endsthereon engaged with the cam pins and resilient means operable betweenthe adjacent ends of the sleeve portions of the shifting forks forurging the shifting forks in opposite directions, whereby the camsurface on the cam ends of the sleeve portions of the shifting forks aremaintained in engagement with the cam pins on the cam sleeve on rotationof the cam shaft.

6. Shifting mechanism comprising a cam shaft, a pair of shifting forkshaving sleeve portions at one end thereof mounted on the cam shaft foraxial movement therealong, cam pins extending transversely of the sleeveportron of the shifting forks, annular discs secured to the cam shaft atopposite ends thereof including the sleeve portrons of the shiftingforks therebetween, a cam plate secured to and extending between theannular discs for rotation with the cam shaft and cam slots in the camplate for receiving the cam pins secured to the sleeve portions of theshifting forks whereby the shifting forks are moved axially of thecamming shaft on rotation of the camming shaft.

7. Shifting mechanism comprising a shaft, (1 pair of shifting forkshaving sleeve portions at one end thereof mounted on the shaft for axi lmovement therealong, cam pins extending transversely of the sleeveportions of the shifting forks, a cam plate mounted adjacent the sleeveportions of the sh fting forks for movement relative thereto and camslots in the cam plate for receiving the cam pins secured to the sleeveportions of the shifting forks whereby the shifting forks are movedaxially of the shaft on relative movement between the cam plate andshifting forks.

8. Shifting mechanism comprising a pair of shifting forks, meansslidably mounting the shifting forks for axial movement toward and awayfrom each other, a cam plate mounted adjacent the shifting forks formovement relative thereto and c m slot and cam pin means operablebetween the shifting forks and cam plate for shifting the forks axiallyon relative movement of the cam plate with respect to the cam forks.

9. In combination, an output shaft, first, second, third and reversegears rotatably mounted on the output shaft, means for rot ting thefirst, second and third gears in one direction, and means for rotatingthe reverse gear in the opposite direction, separate clutch structuresmounted on the output shaft for rotation therewith and movement axiallythereof between the reverse and first and between the second and thirdgears, respectively to engage the gears to produce rotation thereof withthe output shaft in accordance with the axial position of the clutchstructure on the output shaft, a pair of shifting forks engaged with theclutch structures for axial movement thereof with the shifting forks,means slidably mounting the shifting forks for axial movement toward andaway from each other. a can: plate mounted adjacent the shifting forksfor movement relative thereto and cam slot and cam pin means operablebetween the shifting forks and cam plate for shifting the forks axiallyon relative movement of the cam plate with respect to the cam forks.

IO. Shifting mechanism comprising a cam slide, shifting forks positionedon the slide for axial movement therealong, resilient means actingbetween the shifting forks for urging them away from other along the camslide, a cam surface on one of the shifting forks and cam slide and acam follower on the other of the shifting forks and cam slide, said camsurface and cam follower being engaged with each other for relativemovement of the shifting forks on the cam slide in response to relativemovement of the cam surface and cam follower.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 901,456 10/1908 Loitron 74-3375 1,221,925 4/1917Trot! 74337.5

FOREIGN PATENTS 18,872 10/1900 Great Britain. 766,724 7/1934 France.

ARTHUR T. McKEON, Primary Examiner

